foo.c: In function 'main':
foo.c:6:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&x,&y);
   ^~~~~~~~~~~~~~~~~~~~
foo.c:7:7: warning: iteration 6 invokes undefined behavior [-Waggressive-loop-optimizations]
   a[i]=0;
   ~~~~^~
foo.c:5:2: note: within this loop
  for(int i=1;i<=7;i++){
  ^~~

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